Dual synergistic modification of Pebax 2533 membranes with sorbitol and silver nanoparticles for enhanced CO2 separation efficiency

CO₂ separation from N₂ and CH₄ is increasingly important due to environmental and industrial concerns. Membrane-based separation using polymeric materials offers advantages such as energy efficiency, easy processing, and cost-effectiveness. In this study, mixed matrix membranes (MMMs) based on CO₂-philic Pebax 2533 were fabricated and modified in two steps to enhance CO₂ separation performance. In the first step, Sorbitol was incorporated at various loadings (5-20 wt%), with 15 wt% found to be optimal, achieving CO₂ permeability of 394.5 Barrer and selectivities of 13.11 (CO₂/CH₄) and 48.70 (CO₂/N₂) at 30 °C and 2 bar. Sorbitol enhanced membrane crystallinity and thermal stability, as confirmed by FTIR, DSC, and TGA. In the second step, Ag nanoparticles (AgNPs) were introduced (up to 5 wt%) into the Pebax/Sorbitol matrix to exploit facilitated CO₂ transport mechnisem. FESEM showed changes in morphology and increased chain rigidity. The optimized membrane (P/S-15/Ag-5) exhibited a 19.5% increase in CO₂ permeability compared to P/S-15, while maintaining the selectivities. The combined effect of Sorbitol and AgNPs led to improved thermal and separation properties, making the developed MMMs promising candidates for efficient CO₂ separation applications.